KR20020071897A - Alkaline composition, apparatus and method for conditioning scale on a metal surface by spraying - Google Patents

Abstract

A composition and apparatus and method for aqueous spray conditioning of scale on metal surfaces. An aqueous solution having a base composition of an alkali metal hydroxide is used. The aqueous solution may contain additives to improve the performance of the salt. In one embodiment, the solution is used to condition the scale on a strip of stainless steel. The strip of steel is at a temperature between the melting point of the alkali metal hydroxide in anhydrous form and a temperature at which the Leidenfrost effect appears. One or more nozzles is provided to spray the solution, and the heated strip is passed by the nozzle or nozzles where the solution is sprayed on the surface or surfaces of the strip that have the scale or oxide. The invention also includes the apparatus and control thereof for the spraying of the solution.

Description

Technical Field [0001] The present invention relates to an alkaline composition, an apparatus and a method for conditioning a scale on a metal surface by spraying,

The descaling of metal strips, especially stainless steel strips, has traditionally been in many forms. The simplest technique relates to the pickling of strips in mineral acids such as sulfuric acid, hydrochloric acid, hydroperic acid, nitric acid, or mixtures thereof. It works with some degree of stainless steel with a very light scale; In most cases, more acid pickles are needed. In such cases, various compositions and techniques have been developed to condition the scale before the acid water treatment. Typical compositions for scale conditioning include mixtures of alkali metal hydroxides and alkali metal nitrides with various other additives such as alkali halides, carbonates, and / or other oxidizing agents. Often these are referred to as descaling or scale conditioning salts. Conventional techniques for using such compositions are in the amorphous state where the strip is dissolved at elevated temperature, i.e., at a port of 800-1000 DEG F, through migration after the acid treatment. While this works well in many cases, there are certain deficiencies in this technique in many instances. In addition, the dissolved corrosion bath requires a submerged roll that is difficult to maintain and can cause fusion of the descaled strip surface. Additionally, there is a problem of drag-out of the dissolved composition, since the strip exits the port of the dissolved composition, which moves a certain amount of the dissolved composition, especially at high strip speeds. In addition, the composition of the melting tank is limited to compounds with long term stability at elevated temperatures.

Other techniques for descaling are disclosed in U.S. Patent No. 3,126,301, entitled " Molten Salt Spray Process for Descaling Stainless Steel, " issued March 24, 1964, and U.S. Patent No. 5,272,798, issued Dec. 28, for Descaling Metal Strip ". These patents describe a method and structure for spraying molten caustic-containing compositions into a moving strip of steel to condition the scale after the scale has been acid treated. They provide several advantages in several examples of techniques using ports of dissolved materials. However, they also have defects in many instances. They require hot nozzles and the composition must be maintained at elevated temperatures, i.e., 800-1000 ° F.

Therefore, there is a need for an efficient, low-cost, and efficient technique for conditioning the scale of metal surfaces, especially stainless steel strips and the like.

In general, the present invention relates to the surface conditioning of oxides or scales on metal surfaces, more particularly strips of metal, and more particularly to the surface or scale of oxides on stainless steel strips. Stainless steel is an iron alloy containing about 10% or more of chromium to enhance corrosion resistance and antioxidation. Also, some stainless steels include nickel, molybdenum, silicon, magnesium, aluminum, carbide-formed bodies and other elements. The present invention is also applicable to alloys including nickel, which are the main elements of superalloys, titanium alloys and cobalt alloys. In a more specific embodiment, the present invention relates to aqueous spray conditioning.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an annealing line incorporating a scale conditioned area in accordance with the present invention. FIG.

2 is a photograph of the surface of a hydrothermally treated stainless steel sheet according to the present invention.

3-5 are photographs of the surface of a stainless steel sheet showing laden frost effects after treatment and acid water treatment at the temperature of the present invention.

In accordance with the present invention, in one embodiment, a metal surface, particularly a stainless steel strip, may be used to remove or condition oxides or scales in other workpieces, such as other metal bars, or even in separate operations. There is provided a composition and apparatus and method for using a composition for aqueous spraying to remove or condition oxides or scales. Basic solutions of alkali metal hydroxides, such as sodium hydroxide and potassium hydride, or aqueous solutions with a mixture of sodium hydroxide and alkali metal hydroxide, such as potassium hydroxide, are used. The aqueous solution may contain certain additives to improve the scale removal ability of the salt. In one embodiment, the solution is used to condition a scale or surface oxide on a strip of stainless steel. The strip of steel is at a temperature between the melting point of the alkali metal hydroxide in the amorphous form and the temperature at which the lienfrost effect occurs. One or more nozzles are provided for spraying the solution and the heated strips are transferred to a nozzle where the solution is sprayed onto the surface of the strip with scale or oxide. The invention also includes a device and a control for spraying the solution.

1 shows a block diagram of an annealing and acid water treatment line incorporating a scale conditioning and hydrothermal treatment unit according to the present invention, with reference to the drawings. It is believed that the annealing and acid water treatment lines incorporating scale-conditioning units are known in the art. However, the present invention uses an improved scale conditioning technique related to annealing and arithmetic processing lines.

This line has an uncoiler 10 that is conditioned to support and unwind the steel coil 12, in which the coil of steel is annealed and hydrothermally treated to remove the scale formed during annealing. Uncoiler 10 loosens steel from coil 12 with pre-heating furnace 14 and steel strip 13 passing through annealing furnace 16. The strip then enters a cooling zone (18) containing at least one variable speed fan (20). Other means of achieving various cooling may be used as flow control dampers, ventilators, etc. (not shown). The fan 20 cools the strip 13 to a predetermined temperature as described. In addition, the one or more fans 20 may be used to cool the strips 13 of steel. The temperature of the strip 13 when it emerges from the cooling zone 18 is measured by a temperature-sensor device, such as an infrared temperature sensor 22.

From the cooling zone 18 the strip 13 enters the scale conditioning zone 24. In this zone, the scale conditioning solution is sprayed onto the upper and lower surfaces of the strips 13. Spray solutions and methods as well as other variables are described shortly. The scale conditioning zone 24 includes an upper nozzle set that is one of those shown at 28 for spraying onto the upper surface of the strip 13 and a lower nozzle set that is shown at 30 for spraying on the lower surface of the strip 13 And a first or initial set of nozzles including a set of bottom nozzles. A second or backup set of spray nozzles comprising an upper nozzle that is one of those shown in Figure 34, and a lower nozzle that is one of those shown in (36), may optionally be added to assure coverage, if desired, . (Of course, only one set of nozzles may be required in many instances, or more than one set of nozzles may be needed in various cases depending on the speed and width of the strip 13 and other factors.) The nozzles 28, 30 ), (34) and (36) are of the type capable of receiving the liquid and spraying the liquid with very fine granulated droplets on the strip (13) of steel. The nozzles may be air atomizing type VAUs supplied to Spraying Systems Co. While air-granulating nozzles are described, other spray-forming techniques that provide adequate granulation / droplet size, such as high-pressure nozzles, can also be used effectively. Special techniques such as electrostatic precipitation can be used to enhance the transfer efficiency. A rinse zone 38, shown in dashed lines, is provided adjacent the spray zone 24. Optionally, the rinse may be a spray type or an immersion type. In the immersion type, it is carried out by moving the strip under a rubber dipping roll submerged in a rinse water tank, and in the spray type, the rinse is applied to the strip passing through the arrangement of the water spray nozzle supplied with clean water, Pump. Optionally, the surface analyzer 42 is provided near a nozzle 28 that monitors the strip surface to detect under-conditioning. The analyzer 42 may be an infrared scanning system or other machine vision system. One suitable infrared system is Landscan, commercially available from Lan Instruments International Inc. < Desc / Clms Page number 2 > The analyzer provides the input to the line dynamics execution system to be described.

Following the rinse zone, the strip is guided by a set of conventional tracking and bridle rolls 44. This set of rolls 44 maintains the strip on the track and maintains the appropriate tension in the strip.

Generally, the strips 13 of steel go to the sludge treatment area. Generally, the acid water treatment includes one or more acid tanks, even though acid spraying is used. The multiple acidity treatment may be required at various stages of the stainless steel as illustrated in (48), (50) and (52). Rinse tanks 49, 51 and 53 are provided following the hydrothermal treatment tanks 48, 50 and 52, respectively. Typically, the tank 48 comprises a sulfonic acid and the tanks 50 and 52 comprise a mixture of nitric acid and hydropurine acid or nitric acid. One or more of these may be used in any given stainless steel strip 13 depending on factors including the composition of steel, the thickness of the oxide, and many other factors known in the art. In addition, mixtures of different acids and acids are used, which are well known in the art.

Following the arithmetic treatment and the generation of the strips 13 from the rinsing, the strip is reattached to the recoil 54. In this section, all scale conditioning and arithmetic operations are complete.

The liquid scale conditioning solution sprayed on the strip 13 by the nozzles 28,30,34 and 36 is applied to one or more liquid phases having temperature sensors 57,59 and 61, Is supplied from the product conditioning containers 56, 58, and 60. The reason for multiple containers is to store other solutions that are necessary or desirable in different grades of steel and / or storage additives in a base solution that can be mixed in one line to provide the desired composition. Containers 56, 58, and 60 are provided with outflow pumps 62, 64, and 66 to pump liquid from their respective storage vessels. Flow to the controllers 68, 70 and 72, respectively, from the outlet side of the pumps 62, 64 and 66, respectively. (The various flow pumps 62, 64, It is believed that it is possible to combine metering and flow control capabilities in a single unit by eliminating the need for a flow controller, even though a flow meter is preferred, using flow conditioners 68, 70, and 72 The liquid is supplied to the nozzle supply line 74 including the in-line mixer 76 to ensure complete mixing of the product delivered from the two or more storage vessels 56, 58, . Lines 80, 82, 84 and 86 supply the liquid product to the nozzles 28, 30, 34 and 36, respectively, sprayed onto the strip 13, The flow sensors 87, 88, 89, 90 and the metering valve 92, and the flow sensors 87, 88, 90, and 90, respectively, are monitored and conditioned by the spray nozzles 28, 30, 34, (94), (96), and (98) are provided on lines 80, 82, 84, and 86, respectively.

Another method of the composite storage vessel is to use a single vessel containing the concentrated feedstock so that there is no additive in the solution, and a second vessel containing the additive. The first vessel supplies the raw material to the arrangement of the first nozzle and the second vessel supplies the raw material to the downstream arrangement of the second nozzle. This is feasible and undesirable because of the solubility limitations, ion-exchange, precipitation, and the results of in-line mixing of other concentrated solutions such as, for example, nozzle clogging, filter blinding .

The system control includes a task line system input to perform the annealing line, and a line dynamic task system 112 that receives the output line variation 114. A scale conditioning process control system 120 is also provided that receives from the line dynamic operation system 112 to the control variant output.

Before describing the operation of the line in detail, the method description of the present invention is given. In accordance with one embodiment of the present invention, an aqueous solution comprising an alkali metal hydroxide is prepared by dissolving or dispersing, in a solution, a mixture of at least one material selected from the group consisting of stainless steel or other materials having a strip occurring at a temperature above the melting point of the material in substantially amorphous form, And sprayed in the form of droplets on a strip of metal. As used herein, the term " laden frost effect on strip " reveals a patch, or spot of non-perfect scale conditioning, which is the surface appearance of the strip or spot. This is believed to be due to the laden frost effect in the aqueous solution of the chemical if the strip is above the laden frost temperature of the sprayed solution or at a temperature known as the laden frost point. When the strip is above the laden frost temperature of the sprayed solution, a thin film of sprayed liquid is applied to the surface of the strip, in order to prevent the droplets from contacting the surface of the strip, It is converted to a vapor phase blocker between the droplets. The laden frost effect is well known and is described in many publications. Two such publications are described in "Disk Model of the Dynamic Leidenfrost Phenomenon" (Martin Rein of the American Physical Society DFD96) and "Miracle Mongers and Their Methods" (Harry, published in 1920 by EP Dutton Houdini, pp. 122-124).

Figure 2 is a photograph of the surface of a type 304 stainless steel sample that does not exhibit a laden frost effect after treatment in accordance with the present invention, the treatment being described shortly; Figures 3 to 5 are surface photographs of a type (304) stainless steel sample that exhibits laden frost effects to varying degrees after scale conditioning (Figure 5 is the worst) outside the scope of the invention and the hydrothermal treatment. With reference to Figures 3-5, it should be noted that there is an area with incomplete scale conditioning where scale conditioning is complete, i.e., white or gray areas as well as black areas. This is because some drops exhibit a laden frost effect with dark spots and some drops of droplets do not experience or overcome the laden frost effect and are therefore effective for scale conditioning of white or light areas. Thus, as used herein, the term " below the temperature at which the laden frost effect occurs " refers to the temperature at which there is an undefined scale in the form of dark spots after scale conditioning and continuous acid water treatment according to the present invention. The surface as shown in Figure 2 is an example of a temperature at which the laden frost effect is absent, and Figures 3-5 are examples of temperatures at which the laden frost effect is present.

Other samples as well as the examples of Figures 2 to 5 are prepared and processed as follows: The samples are 4 x 6 inch panels of 0.025 inch gauge type 304 stainless steel. Each sample is heated to about 1950 F in air and removed and fixed in the test fixture. The samples are cooled to the predicted temperature measured by the contact thermocouple. The samples are sprayed with an aqueous alkali hydroxide-containing solution, washed with water and then subjected to a hydrothermal treatment. Table 1 below shows the values for the different samples and deformation used in descaling results.

Temperature → ↓ Concentration 400 F 450 F 500 F 550 F 600 F 650 ° F 700 ° F 750 F 800 F 12.5 wt% P / N G / M G / S - - - - - - 23.5 wt% P / N E / L E / L G / S - - - - - 35 wt% P / N E / N E / N E / L E / M G / S - - - 47 wt% P / N E / N E / N E / N E / L G / L G / M G / S - 60 wt% P / N G / N E / N - - - G / N G / L G / S

Sequence key first letter = conditioning / double lettering = degree of observed laden frost effect

E = very good N = no laden frost effect

G = Excellent L = Slightly

F = not bad M = medium

P = bad S = severe

Note: All tests are performed at 100 fpm transfer rate.

All tests were performed with 304 stainless steel, 0.025 inch gauge

All tests were performed at conditioned flow rates to deposit the same solids.

12.5 wt% @ 117 mls / min flow rate

23.5 wt% @ 60 mls / min flow rate

35 wt% @ 40 mls / min Flow rate

47 wt% @ 30 mls / min flow rate

60 wt% @ 23 mls / min Flow rate

Dwell time after water rinsing is 10 seconds

All samples are acid water treated after spray conditioning and water rinsing:

1) 10 vol% sulfonic acid < RTI ID = 0.0 >

2) 8% nitric acid + 1.5 hydropurine acid @ 10 for 130 < 0 > F

During all tests the feedstock was mixed with sodium hydroxide / potassium hydroxide process.

In Table 1 above, the aqueous alkaline hydroxide-containing solution was found to be stable at a contact time of only a few seconds, i.e., below the melting point of the composition in the case of the process mixed NaOH / KOH salt solution above about 450 및 and below the temperature at which the laden- If sprayed on the sample, it causes an appropriate state of the steel surface.

There are several variations that affect the final product. For example, the concentration of the composition in the aqueous solution should be about 15-65 wt%. In a composition of about 15% or less, the energy required to evaporate a large amount of water consumes most of the suitable heat for use in hot strips, particularly thinner gauge materials, achieving the required dissolution of the precipitated salt and performing a scale conditioning reaction To remove residual heat. Above about 65%, difficulties arise in the manufacture, transportation, storage and delivery of highly concentrated solutions. Heating and insulation of the storage tank, precise heat tracing of the piping, recirculation of the fluid flow path, etc., should all be used due to the elevated temperatures needed to maintain the chemicals in the solution and prevent precipitation and crystallization. In addition, due to the additional corrosion problems that occur, high alloy materials must be used for tank storage, piping and nozzles. Also, the use of supplemental energy to maintain elevated storage temperatures is undesirable. As the concentration of the salt in the solution increases, the upper temperature that can be used without causing the laden frost effect increases to about 700 ° F. However, in more than 40% solids, it is more difficult to include the addition. A preferred concentration is about 15-50 wt%; A more preferred concentration is about 35 to 45% by weight; And most preferably about 40% by weight.

The mechanism of conditioning is compared to conventional molten oxidation vessels, where the metal oxide is converted to a more dissolved, more oxidized state in the salt and subsequent water rinsing, while the residue is more easily removed by the acid water treatment. The conditioning of the present invention is such that the sprayed solution is heated in contact with the metal strip and the water is evaporated and the salt is dissolved as residual heat in the strip and readily reacts with oxides on the strip surface in a few seconds. Although the aqueous solution may not contain any oxidizing agent, the salt film has an oxidizing effect on the surface oxides and converts them to the desired high oxidation state. This is apparently due to the adsorption of atmospheric oxygen by aqueous spray and / or the dispersion of atmospheric oxygen through the molten salt film.

In a preferred embodiment, the salt comprises a small amount of an oxidizing agent or compound, such as a permanganate salt, which catalyzes the oxidation reaction.

Application methods for conditioning salts on metal surfaces are unique and provide the unexpected benefits described above. In addition, an important benefit is the ability to use compositions that can not be efficiently used in conventional amorphous molten salt baths because masses of the material around the surface prevent atmospheric oxygen dispersion. The solution may use additives that may be unstable at normal amorphous melt bath temperatures. In addition, the present invention eliminates the presence of reaction products in the applied salt, allowing complete control of the chemical composition of the salt at the metal surface. Finally, the amount of salt consumed can be conditioned to an appropriate amount. In an immersion system, salt consumption is described by the amount of salt adhering to the surface of the metal as it is mostly removed from the bath.

In many cases, it is desirable to use other salt chemistry when the other metal is treated. While this is impractical in immersion systems due to the large amount of material in the molten salt bath, it can be accommodated quickly and efficiently in instantaneous inventions.

There are several other compositions that can be used to affect the descaling according to the present invention. A preferred basic composition is a process mix of sodium hydroxide (NaOH) and potassium hydroxide (KOH) (42% sodium hydroxide and 58% potassium hydroxide). This is a low molten composition (338 [deg.] F) and is efficient in performing scale conditioning when the water of the solution is evaporated. Other materials may be added to the solution to modify the properties of the solution or composition.

Table 2 below provides specific additives with a benefit, disadvantage, or no (intermediate) effect as compared to a base solution.

Scale conditioning effect of various compounds and additives The compound tested When used as an additive in base descaling, When used as the sole descaler compound, disadvantage middle profit Inefficiency efficiency Acetate, sodium vvv . . Aluminate, sodium vv . . Bisulfate, sodium . . . v Carbonate, sodium . . . v Carbonate, potassium v v Chlorate, potassium v . . Chloride, sodium v . . Chloride, potassium v . . Fluoride, potassium vvv . . Formate, sodium vv v Gluconate, sodium vvv . . Metaborate, potassium v . . Metasilicate, sodium . . . v Molybdate, sodium v . . Nitrate, sodium v v Nitrite, sodium v v Perborate, sodium v . . Perchlorate, potassium v . . Permanganate, sodium * vvv . . Permanganate, potassium * vvv . . Phosphate, sodium acid pyro . . . v Phosphate, monosodium . . . v . Phosphate, disodium . . . . . Phosphate, trisodium v . . Shrubber vvv . . Sulfate, sodium vv . . Sulfite, sodium v . . Tetraborate, sodium vv . . Thiocyanate, potassium vv . . Thiosulfate, sodium vv . . Tungstate, sodium v . . Vanadate, sodium v . .

Code number: v Little

vv clear

vvv Very clear

. Precipitation, low solubility, incompatibility or other physical / chemical

Not tested due to problems

* The table forms alkaline magnesiumates when added to the alkaline base descalcification.

While the sodium or potassium cationic additive or the sole descalcite compound is present, the descaling effect is initially dependent on the presence of a particular anion. Thus, the composition is efficiently carried out with one cation with others, if other factors such as solubility and conversion are the same. For example, Table 2 shows efficient sodium nitrate; Potassium nitrate provides contrasting results, but is much less soluble in base compositions. In many cases, the cations of the additives and compounds being tested are noted for their usefulness.

The compounds or additives listed in Table 2 were tested on Type 316 stainless steel of 0.027 gauge 4 " x6 " panels manufactured and processed as described above with the samples of Figures 2-5 and Table 1 above. Compounds to be evaluated as sole de-scaling agents are tested with a saturated aqueous solution up to a maximum concentration of 40% by weight for highly soluble compounds. Generally, the compounds evaluated as additive are formulated in 5% by weight of a solution containing sodium hydroxide, potassium hydroxide process mixture, i.e. 35% by weight of the mixture which is 12.5% of the total 40% solid. In many cases, additives are determined from initial tests known from reference studies and having very limited solubility in water or a caustic alkali solution, wherein the additive is only introduced at a solids content of 1%. This is the case, for example, with potassium chlorate, potassium perchlorate and potassium permanganate. Thus, these additives may be added in an effective amount of about 1%. Also, certain additives, such as sodium chloride, sodium nitrate, and sodium sulfate, which are provided to be incompletely dissolved in the formulated ratio when first mixed or left alone overnight, may be filtered or entrapped with a clear liquid for testing in need. Note that sodium phosphate is not tested for descaling ability as a solidified formulation, presumably due to large hydrate crystals.

The performance of the compound used as the sole descaler is obviously judged to be ineffective or substantially ineffective on the original dark blue oxide scale with any compounds tested, including those that are efficient as additives. The inefficiency of the conditioning is determined by adding hydropurine acid to the nitrile as described above in the samples of Figures 2-5 and Table 1 after the original scale is in the unmodified form and by successive acid water treatment in sulfuric acid Is confirmed.

The performance of the additives is determined relative to the effect of a 40% solution of the NaOH / KOH process mixture, which exhibits excellent descaling behavior under the selected test conditions (i.e., 500 [deg.] F panel temperature, flow rate of 35 mL / box)

The evaluation criteria include, for example, the appearance of the conditioned oxide for color, opacity and uniformity; Ease of removal of the conditioned oxides by rinsing, wiping, or continuous acid water treatment and final appearance of the descaled metal surfaces, for example, for color, brightness, uniformity and autoxidation from residual oxides. As listed in Table 2, these various criteria may vary individually in magnitude and direction to ensure that there is a particular key factor in the quantitative allocation of the disadvantages or benefit effects of the additives. Of course, the intermediate grade shows no appreciable difference from the performance of the 40% NaOH / KOH process solution.

In general, additives exhibiting various adverse effects substantially completely inhibit descaling as they occur with sodium gluconate, or as they occur with sodium acetate and sucrose. Because these three materials are originally organic materials, they can exhibit a reducing action to prevent proper oxidation and conditioning of the scale. It is believed that potassium fluoride is very harmful to cause a unique blob-conditioned oxide that results in a dripped etched metal surface after the acid water treatment. The remaining harmful additives show more or less non-uniformity or inhibition of the conditioning effect. In more specific examples, this results in some scale remaining on the metal after the acid water treatment. In a more favorable example, such a residual scale is limited to a slightly cooler edge of the panel, suggesting that an undesirable efficient temperature range is narrowed.

The advantageous additives result in a uniformly thinner scale as initially demonstrated by the brightly colored, almost transparent, green-based, gold-conditioned oxides that produce bright and clean metal surfaces after sulfuric acid-only water treatment. By comparison, the 40% NaOH / KOH process solution produces a hazy, much thicker, brown conditioned oxide that requires both sulfuric acid and nitric acid water treatment to produce a completely clean, metallic surface. This benefit is most evident with sodium or potassium permanganate.

Turning back to Figure 1, the operation of the scale conditioning system according to the present invention is as follows:

The temperature of the preheating furnace 14 and the annealing furnace 16 and the velocity of the strip 13 are controlled by the line dynamic working system 112. The worker of the line may determine the strip material, the strip gauge, the strip width, and the strip width by a line dynamic working system 112 that determines the annealing schedule for a particular coil of annealed steel in a conventional manner, as is well known in the art. And other specific process information. This results in the steel strip 13 from the annealing furnace 16 and the cooler 18 at a given temperature and speed. The line dynamic working system 112 also inputs various information, such as gauge, width, and material, to the scale conditioning process control 120. The coil start time is also input from the line dynamic operation system 112 to the scale conditioning process control unit 120. The temperature sensing device 22 and the surface analyzer 42 also provide inputs to the scale conditioning process control 120. Other inputs to the scale conditioning process control 120 include: a storage tank level sensor (not shown); Flow controllers 68, 70, and 72; Individual nozzle flow sensors 87, 88, 89, and 90; Storage tank temperature sensors 57, 59,

The scale conditioning process control 120 provides the output to condition all aspects of the scale conditioning function. These embodiments include control of the fan 20 or other cooling control device to achieve this temperature since the preferred temperature of the strip enters the scale conditioning zone 24 (which should be at least 450 F), and the scale conditioning solution Control of the transfer rates from the containers or vessels 56, 58 and 60 and the vessels 56, 58 and 60, respectively, and the metering valves 92, 94, (30), (34), and (36) through nozzles (96) and (98) The flow of solution from each of the vessels 56, 58 and 60 is monitored by a respective flow monitor 68, 70 and 72. Thus, the flow of solution from vessels 56, 58 and 60 can be monitored or controlled separately. This allows containers 56, 58 and 60 to be used in a number of ways. One method by which such vessels 56, 58, and 60 can be used is to use a separate solution or concentration of solution in each vessel and selected suitable vessels 56, 58, and 60 . Another method by which vessels 56, 58 and 60 can be used is to store various components of the final solution to be sprayed; For example, the vessel 56 may comprise a solution of the process mixed sodium / potassium hydroxide, and the vessel 58 may be filled with a solution of potassium, optionally mixed in the mixer 76, And the vessel 60 may contain water that may be mixed in the mixer 76 to provide the desired solution concentration. These are some examples of how containers 56, 58 and 60 can be used. Of course, if only a single concentration of a single solution is used, only one vessel 56 needs to be provided and, of course, three vessels 56, 58 and 60 may be provided.

Scale conditioning process control 120 controls the flow of the solution for each type of steel based on composition, gauge, width, strip speed, and other relevant factors such as time in the furnace that affects the environment of scale on the surface of the strip And a computer (not shown) in which parameters necessary for spraying are stored. Along with these variables already stored, from the line dynamic operation system 112 to the input from the output to the scale conditioning process control 120, the scale conditioning process control 120 determines whether the amorphous salt is above the melting temperature, The choice of nozzles 28, 30, and 34, if necessary 36, the use of programmed solution compositions, and the like to be used to achieve the speed of the fan 20, The choice of vessel or vessels 56, 58 and 60 and the time required for a new type of strip to enter the cooling zone 18 and the spray zone 24 to achieve the desired concentration. This allows smooth operation of scale conditioning after the selected water treatment in the tanks 48, 50 and / or 52. The surface analyzer 42 continuously monitors the status of the strip. If the surface state goes outside the predicted variable, the computer is programmed to condition the variables to bring the surface state back to the required variable.

In operation, the back-up spray nozzles 34 and 36 are configured such that: 1) the individual nozzle flow meters 87 and 88 indicate that there is no reduced flow or flow in any of the nozzles, or 2) Lt; RTI ID = 0.0 > 42 < / RTI > finds a lack of scale conditioning on any part of the strip surface. The initial detection system may be an individual nozzle flow meter 87 and 88 with an optional surface analyzer 42 as an extra checkpoint. The individual nozzle flow meters 89 and 90 monitor the flow of the backup nozzle spray into the individual nozzles 34 and 36. The lack of flow at any nozzle causes a warning condition with declaration and dialogue of such status to line dynamic task system 112.

The invention in its broader aspects is therefore not limited to the specific details, representative devices, or embodiments shown, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention But is not limited to the examples illustrated or described. Thus, departure can be made in detail without being advantageous from the spirit or scope of applicant's general inventive concept.

Claims (28)

A system for conditioning a scale on a surface of a metal material, At least one nozzle suitable for spraying droplets of aqueous corrosion solution; At least one reservoir for receiving the aqueous corrosion solution in communication with at least one of the nozzles; A drive mechanism positioned to move the metallic material with respect to at least one nozzle; A temperature-sensing device positioned to sense the temperature of the surface of the metallic material before the metallic material passes through the at least one nozzle; A cooling mechanism adjacent to the temperature-sensing device; And A control mechanism for controlling the cooling mechanism in response to a sensed temperature of a surface of the metallic material ≪ / RTI > The system of claim 1, comprising at least one nozzle and at least one second reservoir for fluid in communication with the control mechanism. 2. The system of claim 1 wherein there is at least one second nozzle in communication with said reservoir and said control mechanism adapted to atomize droplets of solution. 2. The system of claim 1, wherein the control mechanism comprises a flow control device for controlling flow respectively from the individual reservoir to the nozzle. The system of claim 1, wherein the metal material is a metal strip. 6. The system of claim 5, wherein there is at least one nozzle disposed on each side of the strip. The system according to claim 1, wherein a mountain water treatment station is provided. The system of claim 1, wherein the control is configured to control a cooling device that cools the surface of the metal material below the melting point of the composition contained in the aqueous solution and below the temperature at which the laden frost effect occurs. 6. The system of claim 5, characterized by a surface area analyzer adjacent to at least one nozzle. The system of claim 1, wherein there is a speed sensing device to sense the speed of the metallic material, wherein the control device is configured to vary the flow of the aqueous corrosion solution relative to the sensed speed of the metallic material. A method of treating a scale on a surface of a metallic material, a) providing a metal material having a scale; b) providing an aqueous solution comprising a mixture of an alkali metal hydroxide or an alkali metal hydroxide; c) controlling the surface temperature of the metal material to a temperature below the melting point of the alkali metal hydroxide or hydroxides in the amorphous form in which the conditioning occurs and the temperature at which the laden frost effect occurs; And d) spraying the solution onto the surface of the metallic material ≪ / RTI > 12. The method of claim 11, wherein the solution comprises sodium hydroxide or potassium hydroxide or a mixture thereof. 12. The method of claim 11, wherein the metal is sprayed with the solution and then subjected to a hydrothermal treatment. 12. The method of claim 11, wherein the concentration of the solution is about 15-65 wt% solids. 12. The method of claim 11, wherein the solution concentration is from about 35 to about 45% solids by weight. 12. The method of claim 11 wherein the concentration of the solution is about 40% solids by weight. 12. The method of claim 11, wherein the surface temperature of the metallic material is at least about 450 [deg.] F and no more than about 700 [deg.] F. 15. The method of claim 14 wherein the surface temperature of the metallic material is at least about 450 < 0 > F and no more than about 600 < 0 > F. 12. The method of claim 11, wherein the metal is a stainless steel strip. 12. The method of claim 11, wherein the solution contains an effective amount of an additive selected from the group of alkali metal carbonates, alkali metal chlorates, alkali metal nitrates, alkali metal permanganates, and mixtures thereof. 21. The method of claim 20, wherein the additive is an alkali metal permanganate. 13. The method of claim 12, wherein the aqueous solution comprises a process mixture of sodium hydroxide and potassium hydroxide. Wherein the aqueous solution consisting of a mixture of sodium hydroxide and potassium hydroxide has about 15 to 65% solids by weight. 24. The solution of claim 23, wherein the aqueous solution has from about 35 to about 45% solids by weight. 24. The solution of claim 23 having about 40% solids by weight. 24. The method of claim 23, wherein the mixture of sodium hydroxide and potassium hydroxide is a process mixture. 24. The solution of claim 23 comprising an effective amount of up to about 1% solids by weight of the alkali metal permanganate. 28. The solution according to claim 27, wherein the alkali metal permanganate is potassium permanganate.